Renault Owner Hacks Car's Navigation System Just to Change the Clock
Jailbreaking my car's navigation system just so I can change the time
A 2014 Renault Latitude owner discovered the head unit's clock settings only appear when a legitimate navigation SD card is inserted — and TomTom's DRM rejects any card without the correct CID. Rather than pay €60 for a replacement card, he reverse-engineered the firmware, built a QEMU emulator, and hunted for exploits to root the device. The mount flags were noexec everywhere, and the updater was signature-checked, but he kept digging.
I don't want maps. I have a phone that I use for navigation. I just want to change the damn time.
- numpad0
I've heard that some Subaru models have 3 clocks in the view of the driver, all on the CAN bus, one being the nav and another being a remote display for the nav, and one that's just there, of which none sync to each others. I've looked up how it happened, and discovered that to just to add insult to injury, at least one uses a uC that has RTC feature but no XTAL pin for 32.768kHz or one of any sane base 2 divisions and uses CPU clock of 15MHz or something for it, so it just drifts away.
I don't understand how Subaru stays in the business. Just how. It's a 4 digit time. Just broadcast it on CAN. Why not.
Also: a lot of these older, completely rectangular sat nav units actually follow what is colloqially known as "2DIN" standards. (cheap import Amazon)Aftermarket units are available and those can be swapped in with just a bit of work. That's what most people do when they have issues with the stock unit installed for their markets.
- jerlam
I had a luxury car from 2001 where the time could not be manually changed, only set to specific time zones. Of course, all the time zone rules had long diverged from its rule set, and it had to be changed four times a year to show the correct time.
This car also inexplicably forced you to manually choose a country, and then a time zone, despite having a GPS that already knew exactly where you were and already had chosen a previous time zone.
Carplay is nice but I would have settled for a non-luxury "clock set" button.
- tom1337890
Awesome write up. Love it. And good thing you documented it, since in half a year you'll need it again.
My takeaway: You should have just gotten the SD card and trusted the previous owner. Sometimes "simple users" do know. ^^
- RajT88
Add to falsehoods programmers believe about time:
It can be changed without the SD card in the car radio.
- strenholme
My car came with a cheap low-quality aftermarket combination car stereo and GPS. It would only play music from discs (no USB support), didn’t even support variable bitrate MP3s, and the GPS didn’t know the car’s location half the time.
I finally replaced the head unit with a plastic bracket and a standard old school in-dash stereo system. Much nicer setup.
It’s the cars which can’t have their head unit replaced with a simple stereo which worry me.
- somehnguy
My 2014 vehicle stopped updating it's time automatically a few years ago. I think some cellular technology was phased out or perhaps the cellular contract GM had for vehicle connectivity expired.
Either way I just manually set the time twice a year now - I guess I'm thankful it still has that option.
When I was playing around with the radio in my girlfriends vehicle there was no option to set manually on the clock screen. Seems like a pretty shortsighted move to not allow that.
- wkjagt
Such a contrast with the mechanical clock in my 1981 Volvo 240. Even my 29 year newer (2010) Toyota Yaris just has a simple 12-hour digital clock (not even AM or PM) with a button to set the time. I really appreciate how simple both are.
- runnr_az
As an Arizona resident, my recent Honda CRV's clock is off by an hour for half the year. Since usually the carplay display overrides the clock, it's no big deal, but it cracks me up that, despite being a professional programmer, I have yet to figure out how to set it correctly